What are the transformer oil testing items? It is introduced in the following aspects
1. Appearance: check whether there are impurities in the transformer oil through external inspection
2. Density: The density affects the thermal conductivity of transformer oil. In severe cold conditions, the density is used to determine whether the ice formed by water in the oil filling equipment will cause the discharge of the conductor above the oil when floating on the oil surface.
3. Kinematic viscosity: Kinematic viscosity mainly detects the cooling and heat dissipation effect of transformer oil to see whether the transformer oil can cool and heat dissipation as soon as possible during long-term operation, so as to ensure the safe operation of the transformer
4. Pour point: The pour point is the low temperature at which the cooled sample can flow. The purpose of transformer oil detection is to check whether the transformer can circulate when it is working at low temperature.
5. Condensation point: The condensation point is the high temperature when the transformer oil is cooled to the liquid level without flowing under the specified conditions, which is more important for the transformer oil.
6. Flash point: the flash point is the low temperature of combustion caused by a certain fire source. The flash point of transformer oil is detected to prevent equipment failure caused by heat generated by high temperature in the transformer.
7. Acid value: If the acid value is too high, the conductivity of the oil will be increased and the insulation of the oil will be reduced. Prevent corrosion of some insulating materials, which will affect the service life.
8. Water soluble acid: When the content of water soluble acid in the oil increases and the oil contains water, it will cause corrosion of solid insulating materials and metals, reduce the insulation performance of electrical equipment, and shorten the service life of equipment.
9. Moisture: Moisture has a great impact on the transformer. Too high moisture directly affects the service life of the transformer and seriously affects the reliability of the transformer oil.
10. Breakdown voltage: The breakdown voltage detection of transformer oil is a very important monitoring means to test the electrical stress tolerance limit of transformer oil. Generally, it depends on the degree of pollution. However, when the oil contains high water or impurities, it has a great impact on the breakdown voltage.
11. Dielectric loss factor: The dielectric loss factor is a common means of transformer oil detection and supervision. When the transformer oil is oxidized or overheated, causing oil aging, or mixing with other impurities, the generated polar impurities and charged colloidal substances gradually increase, the dielectric loss factor will also increase, affecting the service life of the transformer.
12. Interfacial tension: It is an indirect and effective method to detect soluble polar impurities in transformer oil due to aging. When the transformer oil is tested to be in the middle of aging, the change speed of the oil will also decrease, and the oil sludge will increase.
13. Corrosive sulfur: the formation mechanism of cuprous sulfide in transformer oil The corrosion rate of mercaptan to copper increases with the increase of temperature. When the temperature increases from 60 ℃ to 120 ℃, the corrosion rate of mercaptan to copper can increase by about 16 times. In addition, it will also affect the insulation performance of the transformer
The transformer oil detection standard is:
The quality standard brands are 10, 25 and 45.
1. The appearance is transparent, without impurities or suspended solids.
2. Density (90 ℃), Kg/m3 is not more than 895 GB/T 1884/1885.
3. The acid value mgKOH/g is not greater than 0.03 GB/T 264.
4. Pour point shall not be higher than - 7 - 22 Report GB/T 3535.
5. Solidification point - 45 GB/T 510.
6. Flash point ℃ shall not be lower than 140 135 GB/T 261.
7. Moisture mg/L report GB/T 7600.
8. Interfacial tension mN/m shall not be less than 40 38 GB/T 6541.
The inspection of transformer oil is extremely important:
1. During the whole application process of transformer oil, the quality of insulating oil deteriorates due to the embrittlement and mildew of the product oil itself and the environmental pollution of the external natural environment, endangering the insulating layer, heat discharge and arc suppression of the transformer; On the other hand, organic chemical vapor is generated in the transformer oil due to the hot partial discharge of conductors and insulators during the whole operation process of the transformer.
2. In order to better ensure the safe operation of the transformer, it is necessary to carry out oil product inspection and analysis of the vapor in the oil on time for the transformer oil in the whole application process.
3. In accordance with the national standard GB7595-2000 Quality Standard for Insulating Oil Products in Operation and the time management regulations for electrical equipment, it is necessary to carry out timely oil inspection for transformer oil, which is a mandatory inspection service for power plants, substation engineering networks, substations, and enterprise internal substation engineering system software.